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Key Takeaways
- Solana moved Alpenglow to its public testnet, aiming to cut finality from ~13 seconds to ~150 milliseconds
- Alpenglow replaces TowerBFT with Votor, a direct validator-to-validator voting system
- Firedancer and Frankendancer don’t yet support the test, so it runs solely on Agave; mainnet timing remains unconfirmed
Solana has moved its Alpenglow upgrade onto the network’s public testnet, where developers will begin testing a change intended to cut transaction finality from roughly 13 seconds to about 150 milliseconds. The migration marks the first time the upgrade has run on a full copy of Solana’s established test infrastructure rather than a smaller, purpose-built network.
Why Finality Speed Matters
Finality is the point at which a transaction becomes permanent and cannot be reversed. Exchanges wait for finality before crediting customer deposits, cross-chain bridges wait before releasing funds on another blockchain, and merchants rely on it to confirm a payment cannot later be clawed back.
Because Solana’s public testnet uses tokens with no monetary value, developers can test the migration, identify problems and restart the network as needed without putting real user funds at risk. That distinguishes this phase from a mainnet rollout, where any similar restart would affect live transactions and assets.
Replacing TowerBFT With a Faster Voting System
Solana currently reaches consensus, the process by which validators agree on which transactions belong in the permanent record, using a system called TowerBFT. Under that system, validators record votes on-chain and must accumulate enough confirming votes across 32 separate slots before a block is considered final, a process that currently takes about 13 seconds.
Alpenglow replaces that system with a new voting protocol called Votor. Under Votor, validators send votes directly to one another rather than recording each vote on-chain individually, and the network can settle on a finalized block after just one or two rounds of that direct voting, removing the longer sequential chain of on-chain confirmations TowerBFT requires.
Applications built on Solana will continue executing transactions exactly as they do today, and users will not need to change wallets or alter how they send funds to benefit from the faster finality.
Testing Timeline and Software Requirements
Alpenglow has already run for more than four months on a smaller network built specifically for the upgrade’s early testing.
Moving it onto Solana’s established public testnet is intended to confirm that the broader set of computers and services already running the network can transition to the new consensus system together, rather than only in an isolated test environment.
Validators participating in the testnet migration need to run Agave 4.3, the current version of the primary software used to operate Solana, maintained by development firm Anza.
Anza recommended the update to all mainnet validators on Sept. 21, after first rolling it out in stages to validator operators responsible for 10% and then 25% of the SOL token supply used to secure the network, a phased approach intended to limit the impact of any unforeseen issues before wider deployment.
Firedancer and Frankendancer, two alternative validator client programs developed by Jump Crypto, do not yet support the Alpenglow test. Those alternative clients are designed to reduce Solana’s reliance on any single piece of validator software, since a fault affecting Agave alone would not disable validators running a different client.
Their absence from the current test means this initial Alpenglow migration runs entirely on Agave, without that software diversity serving as a backstop during the test phase.
Mainnet Timing Remains Unconfirmed
Anza’s development schedule lists Sept. 28 as a tentative date for activating the broader set of features included in Agave 4.3 on Solana’s main network.
That date is not a confirmed launch date for Alpenglow specifically, and Anza’s own tracking system still listed the testnet migration itself as pending as of early Wednesday, underscoring that the timeline remains provisional and subject to change based on how the testnet phase proceeds.
